@Override
public boolean equals(Object obj) {
    if(obj == null){
        return false;
    }
    if(this == obj){
        return true;
    }//是当Person person3 = person1;时 比较person1与person3的情况
    //不是Person类的对象
    if(!(obj instanceof Person)){
        return false;
    }
    Person person = (Person)obj;//向下转型，比较属性值
    return this.name.equals(person.name)&&this.age==person.ege;

}